Required Configuration Tasks

This section lists the required configuration steps to configure the 2-Port and 4-Port Clear Channel T3/E3 SPA. Some of the required configuration commands implement default values that might be appropriate for your network. If the default value is correct for your network, then you do not need to configure the command.

Specifying the Interface Address on a SPA

SPA interface ports begin numbering with “0” from left to right. Single-port SPAs use only the port number 0. To configure or monitor SPA interfaces, you need to specify the physical location of the SIP, SPA, and interface in the CLI. The interface address format is slot / subslot / port, where:

slot —Specifies the chassis slot number in the Cisco 7600 series router where the SIP is installed.

subslot —Specifies the secondary slot of the SIP where the SPA is installed.

port —Specifies the number of the individual interface port on a SPA.

The following example shows how to specify the first interface (0) on a SPA installed in the first subslot of a SIP (0) installed in chassis slot 3:

Router(config)# interface serial 3/0/0

This command shows a serial SPA as a representative example, however the same slot / subslot / port format is similarly used for other SPAs (such as ATM and POS) and other non-channelized SPAs.

Configuring Data Service Unit Mode

Configure the SPA to connect with customer premise Data Service Units (DSUs) by setting the DSU mode. Subrating a T3 or E3 interface reduces the peak access rate by limiting the data transfer rate. To configure the DSU mode and bandwidth, use the following commands:

Command

Purpose

Router# configure terminal

Enters global configuration mode.

Router(config)# interface serial s lot/subslot/port

Selects the interface to configure and enters interface configuration mode.

eic string—Equipment identification code (up to 10 characters), which is a value used to describe a specific piece of equipment according to ANSI T1.107-1995.

fic string—Frame identification code (up to 10 characters), which is a value used to identify where the equipment is located within a building at a given location according to ANSI T1.107-1995.

generator string—Specifies the Generator number string sent in the MDL Test Signal message; can be up to 38 characters.

lic string—Location identification code (up to 11 characters), which is a value used to describe a specific location according to ANSI T1.107-1995.

pfi string—Specifies the Path Facility Identification Code sent in the MDL Path message; can be up to 38 characters.

port string—Specifies the Port number string sent in the MDL Idle Signal message; can be up to 38 characters.

unit string—Unit identification code (up to 6 characters), which is a value that identifies the equipment location within a subslot according to ANSI T1.107-1995.

transmit idle-signal—Enables transmission of the MDL idle signal message. An MDL idle signal message, as defined by ANSI T1.107, is distinguished from path and test signal messages in that it contains a port number as its final data element.

transmit path—Enables transmission of the MDL path message. An MDL path message, as defined by ANSI T1.107, is distinguished from idle and test signal messages in that it contains a facility identification code as its final data element.

transmit test-signal—Enables transmission of the MDL test signal message. An MDL test signal message, as defined by ANSI T1.107, is distinguished from path and idle signal messages in that it contains a generator number as its final data element.

Configuring Scramble

T3/E3 scrambling is used to assist clock recovery on the receiving end. Scrambling is designed to randomize the pattern of 1s and 0s carried in the physical layer frame. Randomizing the digital bits can prevent continuous, nonvariable bit patterns—in other words, long strings of all 1s or all 0s. Several physical layer protocols rely on transitions between 1s and 0s to maintain clocking.

Scrambling can prevent some bit patterns from being mistakenly interpreted as alarms by switches placed between the Data Service Units (DSUs).

Configuring Cable Length

The cablelength command compensates for the loss in decibels based on the distance from the device to the first repeater in the circuit. A longer distance from the device to the repeater requires that the signal strength on the circuit be boosted to compensate for loss over that distance. To configure cable length, use the following commands:

Command

Purpose

Router# configure terminal

Enters global configuration mode.

Router(config)# interface serial slot/subslot/port

Selects the interface to configure and enters interface configuration mode.

Configuring Invert Data

Delays between the TE clock and data transmission indicate that the transmit clock signal might not be appropriate for the interface rate and length of cable being used. Different ends of the wire may have variances that differ slightly. Invert the clock signal to compensate for these factors. To configure invert data, use the following commands:

Command

Purpose

Router# configure terminal

Enters global configuration mode.

Router(config)# interface serial slot/subslot/port

Selects the interface to configure and enters interface configuration mode.

Configuring Multipoint Bridging

Multipoint bridging (MPB) enables the connection of multiple ATM PVCs, Frame Relay PVCs, BCP ports, and WAN Gigabit Ethernet subinterfaces into a single broadcast domain (virtual LAN), together with the LAN ports on that VLAN. This enables service providers to add support for Ethernet-based Layer 2 services to the proven technology of their existing ATM and Frame Relay legacy networks. Customers can then use their current VLAN-based networks over the ATM or Frame Relay cloud. This also allows service providers to gradually update their core networks to the latest Gigabit Ethernet optical technologies, while still supporting their existing customer base.

Configuring Bridging Control Protocol Support

The Bridging Control Protocol (BCP) enables forwarding of Ethernet frames over SONET networks and provides a high-speed extension of enterprise LAN backbone traffic through a metropolitan area. The implementation of BCP on the SPAs includes support for IEEE 802.1D, IEEE 802.1Q Virtual LAN (VLAN), and high-speed switched LANs.

Verifying the Interface Configuration

Besides using the show running-configuration command to display your Cisco 7600 series router configuration settings, you can use the show interfaces serial and the show controllers serial commands to get detailed information on a per-port basis for your 2-Port and 4-Port Clear Channel T3/E3 SPA.

Verifying Per-Port Interface Status

To find detailed interface information on a per-port basis for the 2-Port and 4-Port Clear Channel T3/E3 SPA, use the show interfaces serial command.

The following example provides sample output for interface port 1 on the SPA located in the first subslot of the SIP installed in slot 5 of a Cisco 7600 series router: